title: Role of IV iodinated contrast material in 18F-FDG PET/CT of liver metastases.
abstract: OBJECTIVE
  The purpose of our study was to investigate the role of IV iodinated contrast material in the evaluation of hepatic metastases at (18)F-FDG PET/CT.
  
  
  METHODS
  We retrospectively identified 39 patients (25 men and 14 women) with suspected isolated hepatic metastases from colorectal cancer who underwent FDG PET/CT. The CT protocol included acquisition of unenhanced and multiphase contrast-enhanced CT images through the liver. At two separate sittings, four readers (two radiologists and two nuclear medicine physicians) noted and characterized all hepatic lesions in consensus, first based on PET and unenhanced CT images and later based on PET and contrast-enhanced CT images. The nature of detected lesions was established by histopathologic or clinicoradiologic correlation.
  
  
  RESULTS
  A total of 178 hepatic lesions were identified, consisting of 137 metastases and 41 benign lesions. Using lesion-based analyses with Obuchowski's method for paired observations, 172 of 178 lesions (97%) were detected at PET/contrast-enhanced CT compared with only 135 of 178 (76%) at PET/unenhanced CT (p = 0.0004). Specifically, 114 of 137 (83%) hepatic metastases were detected on PET/contrast-enhanced CT compared with 92 of 137 (67%) on PET/unenhanced CT (p = 0.012). One hundred thirty-one of 178 lesions (73%) were accurately characterized at PET/contrast-enhanced CT compared with 101 of 178 (57%) at PET/unenhanced CT (p = 0.004).
  
  
  CONCLUSIONS
  IV iodinated contrast material administration improves the detection of hepatic metastases and the characterization of focal hepatic lesions at PET/CT.
authors.affiliation: Department of Radiology, University of California, San Francisco, Box 0628, M-372, 505 Parnassus Ave., San Francisco, CA 94143-0628, USA.
authors.forename: Shiva
authors.initials: S
authors.lastname: Badiee
authors.forename: Benjamin L
authors.initials: BL
authors.lastname: Franc
authors.forename: Emily M
authors.initials: EM
authors.lastname: Webb
authors.forename: Bill
authors.initials: B
authors.lastname: Chu
authors.forename: Randall A
authors.initials: RA
authors.lastname: Hawkins
authors.forename: Fergus
authors.initials: F
authors.lastname: Coakley
authors.forename: Lisa
authors.initials: L
authors.lastname: Singer
mesh_terms: D015179:Colorectal Neoplasms / Q000175:diagnosis*; D003287:Contrast Media; D019788:Fluorodeoxyglucose F18; D007089:Image Enhancement / Q000379:methods; D007479:Iopamidol; D008113:Liver Neoplasms / Q000175:diagnosis* / Q000556:secondary*; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D007479:Iopamidol